PERJUGATE COTTON HYBRIDS 



Amazing Diversity Characterizes Second Generation After Cross, and Affects 



All Characters of Plants, While First or Conjugate Generation 



Shows Great Uniformity. 



Charles G. Marshall 

 Bureau of Plant Industry, U. S. Department of Agriculture, ]]'ashington, D. C. 



DIVERSITY in the pcrjugate 

 generations of cotton hybrids 

 must be a familiar phenomenon 

 to all who have made the 

 experiment of crossing two distinct 

 types of cotton. It has been shown in 

 numerous crosses that have been made 

 between the Egyptian cotton and a 

 series of Upland varieties. One of the 

 most conspicuous examples was af- 

 forded by a series of hybrids between 

 the Egyptian cotton and the so-called 

 "Hindi" cotton, an inferior type chiefly 

 known as a contamination of the 

 Egyptian crop. The experiment of 

 making artificial crosses between the 

 Egyptian and Hindi cotton was not 

 made with any idea of securing superior 

 varieties but in order to learn the range 

 of diversity in the Egyptian stock that 

 might be ascribed reasonably to con- 

 tamination with the Hindi cotton. The 

 results showed that a very wide range 

 of diversity could be induced by hy- 

 bridization. With the advice of O. F. 

 Cook detailed notes were made on a 

 series of plants as a means of recording 

 the nature and extent of the diversities 

 that appeared among the perjugate 

 hybrids.^ 



In 1910 self -fertilized bolls of a con- 

 jugate hybrid plant of Hindi x Egyptian 

 cotton were secured by A. McLachlan, 

 and in 1911 the seed was planted at 

 Bard, California, in order to observe 

 the behavior of the second or perjugate 

 generation. Conjugate hybrids be- 

 tween the same stocks were raised in 

 adjoining rows, and the essential differ- 

 ences between the two generations were 

 shown in a very conspicuous manner. 



Members of the conjugate generation 



were not only uniforaily alike but 

 showed characters intermediate be- 

 tween the two parent stocks. The 

 perjugates, however, were so diverse 

 that no two plants could be found with 

 even a few of their characters alike. 

 Many of the plants would not have 

 been associated with either of the parent 

 types, if their parentage had not been 

 definitely known. Parental characters 

 were not only exaggerated but in many 

 cases entirely new characters were de- 

 veloped. 



EXTENT OF DIVERSITY. 



Even in their general appearance and 

 behavior the perjugate plants showed a 

 most remarkable range of diversity. 

 There were all degrees of size, coloring, 

 habit of growth and earliness of matur- 

 ity. One plant might be large, light 

 in color, strong and upright and late in 

 maturing and the next plant in the 

 row be small, dark in color, weak and 

 drooping and early in maturing. Yet 

 such completely contrasted plants might 

 be full sisters, grown from seed of the 

 same self-fertilized boll. 



DIFFERENCE IN LEAVES AND BRACTS. 



Studies of the different parts of the 

 several plants such as the leaves, 

 involucral bracts, bolls and seeds, re- 

 vealed as great diversity and range of 

 differences among these more detailed 

 characters as there was in the general 

 appearance and habit of growth of the 

 plants. Many combinations of these 

 characters were to be found in the 

 different plants but no two plants were 

 found that appeared to have the same 

 combination, nor was it possible to 



1 Cook, O. F., Hindi cotton in Egypt, U. S. Department of Agriculture, Bureau of Plant In- 

 dustry, Bulletin 210, 1911, and Heredity and Cotton Breeding, Bulletin 256, 1913. 



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